IMHO the Blizzard 1230MkIV is the best 'all round' A1200 Accelerator, It has 50mhz 030 and optional FPU. It can take up to 128mb and you can add FastSCSI II which can take another 128mb Ram!
The ACA's are a good choice too, they can Map a Rom from an image (so if you only have 3.0 Rom you can have 3.1 without buying it) Or you can map your own Custom 3.9Rom with updated modules.
Of course, it's new with waranty but bear in mind there is no FPU and you cannot upgrade the Ram or add SCSI, although to be fair 64mb is pobably more than you'll ever need.
Also, the ACA's can bring out timing issues in some A1200's, so you might end up needing to fix the Motherboard.
There are many, many more options to suit all budgets so you can always ask here if you see something you like before taking the plunge.
All the best,
Steve.