As far as what format I prefer, it really doesn't matter to me. What matters most to me is how I'm enjoying an RP. I really don't care if it's 1x1, group, or whatever you have it. I think the most important is that you're enjoying the story that you volenteered to co-write with xamount of people. If a group RP is your thing, then you're going to share the writer's credit with 2+ people at least; if a 1x1 rp is your thing, then you have 50% of the writer credit.
That's really how I feel about it. If I am enjoying myself, my preference of the number of people, type of rp it is(1x1 or group), genre, and setting takes a back seat to my enjoyment..
Regarding length and level, I tend to go for a high casual at the minimum. No offense to those who are free/mid-cas, but I just find the idea of anything less than HC useless for my own personal tastes. I like to immerse myself into a story/rp and I feel like I can't do that when it's 1-2-liners(free) or 1-2 paragraphs(Low to Mid-Casual) at the maximum. I need details like dialogue and the descriptive paragraphs that help set up said dialouge. I need that character interaction that helps establish these relationship and everything that will follow from that. Not to take a sexual pun, but I need the fucking D-etails man. I don't think I would get that with free/low to mid-cas. I do, however, know that High Casual and above will give me that, so that's why I prefer that level of length in rps.
When it comes to Face Claims, I used to be about anime because I was really about anime roleplays, but lately, I've been finding myself preferring real life faceclaimes as well as real life rps. I think when it comes down to it, my love for anime is diminishing moderately and the aspect of RL is coming in quick. With that being said, I will use anime/VG faceclaims if there is a rp that catches my eye that will call for such an image.
Genre-wise, I don't really have any one specific preference. There are times where I just want a simple, Slice of Life rp with not action or sci-fi elements or magic or anything of the sort. Sometimes a guy just wants to write about the trials and tribulations of daily life such as family drama, drama within the friend circles, relationships, shopping, hanging out with friends, worklife, and the like. I really don't see anything wrong with that.
However, there are other times where the time comes to activate my World-Saving Mode. What that means is that I will enter the state-of-mind that is craving for a bunch of spandex-wearing, cape-bearing, outrageous-asf, power-wielding, nigh-god superhero whose symbol represents hope or some shit like that. In other words, there will come a time where I must give up the aspect of life for saving the day from whatever the powers may be.
There can be other times where I enjoy the fuck out of some sci-fi shit. What this includes is, but not limited to: aliens, intergalactic travel, outer space politics, and technological breakthroughs that are several decades away. Yes, that's right, sometimes a guy just wants to be able to melt some poor sap's face off with a plasma grenade or crush him with such a powerful telekinetic force that it will blow his head off from sheer force. Or perhaps don some powerful blue-like energy that will send the poor fucker flying in the opposite direction. Hell, even some advanced rifles are enough to get my feathers flying.
In the end, I can go for any kind of genre as long as I'm in the mood for it. If the genre doesn't interest me, odds are you won't see me enter such a rp that houses the hypothetical genre.