There was a version of First Word Plus for the Acorn RiscPC, too. I had a copy (still have it, in fact, but I upgraded RiscOS and FWP stopped working...)
...then again, Word has its down-sides, not to mention its cybernetically-enhanced paper-clip. You have to do things the way it wants: resistance is futile.
Then there's the Oric-1 (no, not the perspex computer from Blake's 7).
I had the same problem. I had two finished novels. I was touting them around agents and, to be honest, the decision as to which one I'd send was made on a whim. Depending on what mood I was in, I would decide that one or the other was better, and send it out. In the end one of them interested an agent, but he signed me up on the strength of the second one.
The current situation is that we’ve abandoned both of them and he’s now started trying to sell my third novel.
In the end, you have to present what you believe is your best work. The great problem is, if you’re anything like me, your belief will change on a daily basis!