I'll echo that 'best' is a highly suggestive term, but in terms of which basses will give you a solid value, reliability and flexibility for that dollar amount, here's what I recommend:
Buy used.
There's been mention of the Squier Affinity 5 and I'm wondering if they're actually referring to the Squier Deluxe Active Jazz V, which has gotten quite a bit of press around here. I own one, and what it may lack at it's price point it more than makes up for in terms of out of the box usability. It's also an easy bass to mod, as many a classified ad will attest.
Ibanez ATK - Full disclosure, I own both a Squier Deluxe Active Jazz V and an Ibanez ATK 305 and I could easily use one or the other for all of my gigs that require a fretted bass. The Squier (modded w/ Nordy pickups and an Audere preamp) cops the hi-fi jazz sound and has a wide, comfy (19mm) neck. The ATK has a more aggressive sound, a thinner string spacing, and possibly the best low B of any 34" scale 5-string I've ever played. Not sure if that's common to all ATKs, but mine is perfectly balanced with the rest of the strings.
The Peavey TL-5, mentioned in the above post, is also a fantastic bass that I've owned and heartily recommend.
I'm also a big fan of Carvin, and they're comparatively low resale value can make for some great deals.
Even fuller disclosure - both my Squier and Ibanez are currently for sale as I'm focusing on fretless and upright. Whichever one doesn't sell will become my main fretted. Both are a joy to play.
Good luck,
J.