Firstly, what is your experience level? Have you kept T's before? If not, then I wouldn't recommend H. gigas or H. lividum. One thing you must remember about these 2; H. lividum is only blue when viewed under specific lighting, and that's if you can even see them as they spend most of their lives in holes, and H. gigas hardly ever swims unless forced to. In fact, most tarantulas can "swim" if they had to. I've got a theory that S. calceatum and H. masculata might also be like H. gigas as I've noticed when they're threatened, they head straight for the water bowl and submerge themselves.
As for Advice for new T's, go for the Antilles Pinktoe (Avicularia versicolor) and Singapore blue (Lampropelma violaceoups/Cyriapagopus sp Blue) as soon as possible, as stock is very limited on them. The Singapore Blue is top on my list of the best looking spider around, with P. mettalica on the bottom, just under the curly hair :P
And for Terrestial based T's, I would go for H. gigas, as they are more often seen than H. lividum, and perhaps a Phormictopus cancerides (these are third on my list of best looking spider, I have a huge female that is just gorgeous).
Feel free to ask for more info, I'm online at least once a day now