There are many I like, including some 1911 variants, P35 variants, CZ75 variants, P08 variants, and Beretta 92 variants... but to be different, I will go with the one I have on today:
Ugliest... Toss-up between HiPoint (any) and Walther PPQ.
I'm not brand loyal enough to claim a HK VP70, that thing is ugly, I won't beat the glock to death. I know it's not an auto but the S&W Model 29, a masterpiece. MMMMM
I agree, even though I don't own one, I still think the 1911 probably looks the best. Thankfully, with firearms, looks are hardly the most important when it comes down to it.
Ugliest, in terms of current and popular semi-autos, IMHO, is the Beretta PX4 Storm Subcompact. Just hideous looking guns...chunky and stubby is the only way to describe them.
I personally don't find Glock semiautos "ugly", they are just incredibly boring and spartan.