Maybe this should go in seeds. Perhaps there should be a new subforum for general FTB talk.
I don't really like Jungles, though I need one for my beekeeping endeavours!
I adore the autumn biome trees, but the biome itself is not so great. Too many trees.
It always seems the ocean biomes are a bit too extensive! They're nice, though.
I like plains, because they're plain and rather flat and good for building.
Redwood trees are quite nice. So are fir trees.
I do like mountains. They look magnificent with a building on top and you can drill good hidey holes in them!
Hell biomes are quite nice.
River biomes? Good. Annoying sometimes, but good to fight in! When I'm crossing a river, and a spider is on my tail, I dive down and attack it from below. Good tactic! Well, it's not that good a tactic in FTB anymore with all those nice gadgets.
I like red rock.
Mushroom biomes! Awzum.
Tundra? Sometimes boring. Quite flat, though.
Taiga? I do like wolves! The trees are quite variable, so that's good. Might be boring though. It seems that many people have a grudge against Taiga biomes. It's because one often spawns in these biomes, and they get quite boring. Fortunately in FTB ExtraBiomesXL comes to save the day!
End biomes are quite cool. No monsters but Endermeisters! Classy.
Swamp biomes have lilypads, so I like them. They also have lots more rubber trees than other biomes! They're good to spawn in.
Deserts are nice, but as long as they're not huge. They're flat and don't have many obstacles. Just cacti.
Forest biomes are alright. 'Nuff said.
Any significant ones I missed?