I have two Campagnolo-equipped bikes (10 & 11-speed) and two with Ultegra (9 speed), so I'm familiar with the differences: the Campag shifters have an inner lever like the Shimano setup, but unlike that it shifts to bigger cog/bigger chainring. There's a thumb button (a bit like the old Shimano Sora setup) for smaller cog/smaller chainring. Brake levers just brake. Shifting action is generally described as 'positive', 'clunky' , or as
@vickster notes, 'agricultural', depending on one's perspective. Even after thousands of miles on each system, I still make the odd wrong shift now and again! I prefer Campagnolo, but very happy with the Shimano setups too, not much in it. Cassette choices are, if you want a bigger ratio range, better for Shimano/SRAM than Campagnolo, (Campag offers 12-30 and 12-27 Centaur-level cassettes, but there's no 11-27 option- except from third parties- and no 11-28 at all). As with Shimano and SRAM, you can mix and match 10-speed components from different groupsets, and 11-speed components from different groupsets, but not combine the two. If you go up to 11-speed, you can however use Campag, Shimano or SRAM groupsets with cassettes from any of the others.
Campagnolo has had an unfortunate knack of downgrading specifications on their lower-end groups in recent years- the newer Veloce setup cannot do multiple shifts, and I'm glad I got the first iteration of Athena as they started speccing lower-level cranksets, and again multiple shifting got binned.
Of those bikes, I'd go for the Planet X or the Dolan over the Forme- PX don't offer a bike builder but they will change components if you so wish. Definitely a case of trying frames, and groups, before you buy.