Haven't seen this topic for ooohhhhh, weeks!
Intamin for me. They've had a few duds, sure (those god-awful half pipes for example), but so has every other manufacturer. If you include their flat rides and water rides, too, that pushes them right up to the top of the pile.
B&M are great, but nothing they've been building recently has made me think, "oh wow!" It's all pretty much more of the same for the last few years. Definitely up there as a very close 2nd to Intamin though.
It's no secret that I've got a real soft spot for Togo. No, they're not the best manufacturer, not by a long way, but I find a lot of their coasters to be really fun, quirky, with a lot of personality.
Vekoma take a lot of crap, but I can honestly say I've never really disliked any of their coasters. There's a lot of "meh" in there, sure, but nothing I've completely hated. Maybe I've just been lucky and haven't ridden one of those really rough slcs/boomerangs I keep hearing about.
Arrow. I'm pretty much on the fence with them. Loved Eagle Fortress and Fantasia Special, liked a few others, hated their old corkcrews. Anyway, they're gone now, which makes me pretty much forget about them when these topics come up "occasionally."
GCI, CCI, Gravity Group. I think from all 3 of these manufacturers, I've only ridden Megafobia. Loved that, but not going to pass judgement based on one coaster
Gerstlauer Just realised I've only ridden Troublesome Trucks. I'll be in more of a position to judge this summer.
Maurer Sohne. Again, I need to ride more. They seem to make the best spinners (Intamin's Comet Express excepted), but that's not saying much. I loved Venus, though. Definitely one of my favourite loopers. Too bad they only ever built one.
Mack. Kings of the powered coaster, and manufactured my favourite mine train, Gran Montserrat. Again, need to try more.
S&S. Only tried Dodonpa. I still to this day can't decide if I actually liked it though. Such a weird one. I can never get excited by S&S. Don't know why.
Pinfari. Their coasters can be fun, in an "oh ****, what the hell is going on" kind of way, but absolutely zero to make me label them as "good."
Huss. Their Giant Frisbees are great, but Intamin's Gyro Swings beat them slightly, mainly on having more comfortable seats. Not much in it though. Otherwise, I'm not impressed be Huss. The suspended top spin is ok, but I'm sick of the regular model. Plus, they make the WORST drop towers on the planet, bar none.