I see your prices are in £ so I assume you’re in the UK.
My advice would be don’t buy too cheap - I have 4 different adaptors that were bough mainly for development/testing (I normally use Ethernet) ranging in price from £4 to £14 and the cheapest one has very disappointing performance.
My cheapest one is a £4 Tenda W311N which uses the same Ralink rt5370 chipset as your third option - my advise would be to avoid it as it is slow and seems to have limited range as well. (Although the Tenda one does not have an external antenna)
The other two dongles don’t give any indication of what chipset they use that I can see and have very generic names, so I can’t even identify them to give an opinion on them.
IMHO one of the best performing but still good value for money adaptors that works very well in OSMC (only since RC2 mind you) is the TP-Link TL-WN823N - available for £10 from PC World:
On my Pi 2 I’m seeing real world iperf performance as fast as 116Mbps in the same room and 90Mbps from downstairs to upstairs and it seems to be rock solid. I can stream video in excess of 40Mbps between rooms on the Pi 2, something which none of the other three adaptors (including the more expensive 5Ghz AC one) can.
It doesn’t have AC or 5Ghz but it does have dual stream MIMO which few small USB adaptors do. This roughly doubles performance over single stream adaptors, provided your AP supports MIMO.
You won’t see that level of performance on a Pi 1 due to the much lower CPU performance but it should still be very reliable.
Anything less than about £7 in USB wifi adaptors is false economy I think - performance will be disappointing and you’ll just end up buying a more expensive adaptor to replace it anyway.
I actually think I was originally looking for a USB to LAN adapter… again CHEAP as if its more than £10 I might as well junk the Model A and buy a B or a 2!