A 100 watt amp will give you enough power and sound for most any gig you will play. Ampeg, and Fender makes good amps. Ashdown is top of the line. I have a old Peavy Mark IV series head that can push 210 watts at 4ohms and 300 watts at 2 ohms. It should be around 115- 120 at 8 ohms. It all depends on your finances I guess.
This may be an option. The most bang for your buck. 120 watts for $149 and free shipping.
Buy Behringer BX1200 Ultrabass 120W 1x12 Combo online at Musician's Friend