I like them long and thick and juicy.

Depends on my mood. I like both games you sink dozens of hours into, plus games you can "play in a day". Same is true of genres - it's a good thing to mix things up so you don't get burned out playing too much of one thing. What I am less tolerant of though is 'grind for the sake of grind' and artificial padding, ie, I don't mind 80hr games if they feel like they have that amount of content naturally (Dragon Age Origins, NWN + expansions, etc). 20hr games padded out by +50% though via mindless repetition or 'obvious filler side-quest spam' / having to 'farm' unlocks for the sake of it now feel more tedious and cheap than fun.

Depends on the games in question, how gripping they are, how enjoyable their mechanics, how much of interest there is to explore etc., and also on the genre. I prefer adventure games to be under 10 hours, RPGs to be over 10 hours, for example. Tendentially, I prefer to sample more games and finish them in shorter time, as opposed to sticking to one game forever. But I also think length is not a good measure for quality. It all depends with what the game hours are filled, whether it's just repetitive, tedious filler content and mechanics that artificially prolong the game and delay the ending, or truly original, surprising, exciting ideas and/or highly entertaining gameplay that keep you glued to the seat, not realizing how time flies. I don't really like to replay games though. I still have to find the game that does not bore with me with repetition on the second playthrough, no matter how much it claims to be replayable.

Depends on game, mood...

When I'm playing some really long game (like open-world RPG) I sometimes use really short games (<10h) for a break. In between those huge games some medium sized game(s) (20-40h) are welcome.

Linear action/FPS games I tend to start wanting them to end after 10 hours or so. More open ones like Far Cry or Rage I can enjoy playing longer, but usually I'm still ready to move on at some point and skip the side stuff to finish it quicker. I think a dozen hours or so is the sweet spot for those genres.

RPG hybrids like Deus Ex, or "real" RPGs like Risen or Fallout... with those I guess the longer the better. A nice thing about games like that is that you can kind of go to the end as soon as you want. Just stop doing sidequests and mainline the main quest and you'll be done pretty quick. I tend to only play one character for 40ish hours and save a bunch of sidequests for future playthroughs. For example in a game like Skyrim I will ignore the mage's guild if playing a fighter my first time, saving it for a future mage playthrough. I'm not a completionist at all.

About 10 years ago I would easily have sided with size... the larger the better... but today I prefer games that have sufficient content to justify their size. If a game is long but doesn't have the content to justify its size (ie Assassin's Creed Odyssey or Mafia III), I've grown to resent the loss of time. If a game is short but packed with content, I'm fine with the proposition.

It seems that the older I get the shorter I want the game to be. This really depends on the game and on how much I can tolerate. When I was younger I could sit hours after hours on FPS and RTS. Now those two are more than often a chore to play through (at least the newer titles).

Horror games is just a hit and miss... mostly misses actually. I just pray for a short game or I just quit.

Nowadays I seem to have regressed back to my earlier fascination and enjoyment of RPG/PnC games. I usually don't play as much as I did, mostly around holidays and sometimes weekends. However, if the game does have a reasonable amount of content and not grindy/annoying/boring, I don't mind the game to be long, like Syberia, TES, Enderal, Witcher 3, Fallout, and Grim Dawn.

But MMOs like EVE it just needs too much time and investment that I probably won't be coming back to again. Maybe... ;)

Depends on the game, really.
As others have mentioned already: an RPG with an epic story, fascinating lore and probably a whole world to be rummaged through, should definitely last longer than a - let's say - jump 'n' run.

That's not to say that all RPGs have to have hundreds of hours of playtime...to give an example: when I played Two Worlds, I was burned out after roughly 25 hours, and deliberately went into the final fight, despite still having a dozen or so side quests open.

After these 25 hours of playtime I simply was feeling bored inside its world and wanted to bring the game to a proper end. So I did, and I never looked back, since.

A jump'n'run on the other hand, is something, I can return to over the years, over and over again - it never overstays its welcome, so to speak - therefore it never bores me.

Edit: typo

Personally, I prefer short games with high replay value. There's a reason I really enjoy playing Columns from time to time (a game can be finished in a short time, and there's even a mode where the game only lasts 3 minutes at most). Even the famously difficult Tetris the Grand Master games are very short; if the game isn't over within 15 minutes, you're playing way too slowly (and actually lasting this long without clearing the game is difficult if it's even possible) SaGa 1 is one of my favorite RPGs, and it is incredibly short by RPG standards (though still much longer than Columns).

Personally, I wish there were more RPGs that were about the length of SaGa 1, but which gave you different options for party construction. 10 hours is IMO too long here.

I'm really enjoying Tangledeep right now, but considering that the game has procedural generation, multiple ways to build your character, and meta-progress (can keep things between playthroughs), I wish it were much shorter, with a bigger emphasis on meta-progress. (If I were to make a roguelike, I think I'd want it short with meta-progress, and I would also include a "chaos" mode that increases the randomness to the point where powerful items and monsters can appear early, or even tothe point of no longer being guaranteed winnable.)

Short answer - short games.

Yes, I prefer games :-D

I couldn't agree more. As long as the game is enjoyable, I don't mind its length. While it's more and more difficult to have longer playing sessions, I don't hesitate to give a try to long RPGs. The only exception, as few other people mentioned as well, are MMOs. Those are straight up time killers and I really can't afford to do that anymore.

I only finish short good games, but also like longer game and prefer them to shorter ones.

I used to love games that were longer with a bit of grinding in them (for old school RPGs) and I played the HELL out of some long epics, spending tons of time on them. Now adays I prefer somewhat shorter game experiences because I may get some free time for a week, but I doubt I'll remember where I am when I get back to it in 3 or 4 months when I finally have enough free time to sink into a good game again. It also takes a LOT of motivation to play some games these days. Like I will boot up to the title screen and quit because I just lack the will to go through any farther. Getting older sucks!