It is such a personal and image specific thing, I would suggest sample packs from Hahnemühle, Canson, and Harman. Harman purely for their Gloss Baryta, Gloss Baryta Warmtone, and mat canvas.
Personal favourites include:
Harman Gloss Baryta (320, soft gloss; also available in 17 x 25 inches which better matches the 3:2 ratio of dSLRs)
Canson Baryta Photographique (310, lustre)
Canson Rag Photographique (310, smooth rag, but less expensive than the more popular Hahnemühle Photo Rag 308)
Hahnemühle German Etching (310, medium textured, but holds detail well where ink goes down)
Canson Arches Aquarelle (310, water colour rag)
If you are after middle weight papers (250-280 g/m² range), then there are too many to go through, but Epson Fine Art Velvet is a really nice paper.