Which RAID Controllers to pick/avoid?

I'm setting up a dedicated linux postgres box with 2x300GB 15k SAS drive in
a RAID 1, though if future load dictates we would like to be able to upgrade
to RAID 10. The hosting provider offers the following options for a RAID
controller (all are the same price):

ADAPTEC 3405 RAID Controller
ADAPTEC 4800 RAID Controller
LSI MegaRaid 8308 RAID Controller
ADAPTEC 5405 RAID Controller
ADAPTEC 5405Z RAID Controller
ADAPTEC 5805 RAID Controller
ADAPTEC 5805Z RAID Controller

However, they can't guarantee that any particular RAID controller would be
in stock when they are building the machine, so basically I would like to
know if any of these cards are sufficiently better or worse than the others
that I should either a) wait for a particular card or b) avoid a card.

Also, I am planning on replicating this box to a standby machine with
streaming replication. Given this, is there any reason not to use the write
cache on the RAID controller assuming it has battery backup? My though
being even in a worst case scenario if the BBU fails and the master DB gets
corrupted, the standby (not using any write cache) would still be ok sans a
few seconds of data (assuming the replication was keeping up, which would be
monitored).

-Dan