Stirling. I literally have to force myself to use anything else these days, and when I do I'm dissapointed. I have a sad tub of Prorasso Red....
Not only is the performance of Stirling fantastic, but the variety of smells and cheap price is unbeatable. You can get very large and cheap (~$2) samples, as well. Sometimes it is the scents you didn't think you'd like that become favorites....
Go with Arko.
If you want to go large and treat yourself, MdC is unrivaled. The amount of lather you can whip up after a few swirls is almost criminal.
I will throw my hat in for Stirling and Barrister and Mann's. I got the Sampler from Barrister and Mann and from Stirling I love the Barbershop scent. Still waiting till I run out of soaps to try some more scents from Stirling….it is that good beside Stirling and the Strope Shop I think I have found my two soaps.
Stirling is great for variety & value. If you might have hard water, Petal Pusher Fancies is pretty awesome. It has a similar post shave face feel as Synergy, if you liked that.
I would try for Tabac, RazorRock, Arko and La Toja as your next more mass produced soaps. I would say that RazoRock is an artisan soap but is very popular.