THe Basiq is really an entry-level unit, and not up to usual Antec quality standards. The only reasonable priced Antec models I would consider would be the Earthwatts, Neo Eco or High Current Gamer models. The TruePower units are good too, but I think those are usually pretty pricey in comparison.
I actually have that exact Seasonic unit, except for the modular version. Seasonic "S12II" PSU's are non-modular, and "M12II" units are just modular twins of the same power output S12II unit. That is a top-notch power supply that has really served me well for overclocking purposes. I attribute part of the reason I was able to overclock my Phenom 965 so easily to the quality of the PSU, since I jumped from 4.1 to 4.3ghz just by switching from the jenky Coolermaster unit I had been using.
From Corsair, the line you'd want to look into is the TX models. They are the ones that come in both modular and non-modular configurations, and are also considered to be their entry level of "performance" power supplies. The CX and VS aren't bad, but I wouldn't write home about them either.
Modular supplies are pretty hard to come by for reasonable prices. I think the Seasonic M12II 520w would be the most common, along with the Antec High Current Gamer 520M, and Corsair TX650M. All three are great in my book. Mind you, those are all "partially" modular, meaning the 24-pin power supply to the mobo is not removable, but obviously you're going to need that for any application. The only advantage of "fully" modular is if you have a case that makes running the power cables really tricky, and could be made easier with hooking up the supply-side last. The OCZ ZT 550, 650, and 750 are all very good quality, fairly reasonable price fully modular units if by chance you find them.
I would toss out there that the Rosewill "Hive" and "Capstone-M" series PSU's are also viewed in high regard by most people who have used them. I personally am a little hesitant based on the company's hit-and-miss record in generally everything with their name on it. Still, they are rated 80+ bronze and 80+ gold respectively, and are more affordable than any similar spec units from the major players.