The America/Speedmaster is a good learner's bike. They're well behaved, pretty forgiving, and have enough "oomph" to not stay with you once you've learned how to ride. They're also uncommon enough that you'll look great & stand out even when in the middle of a bunch of harley clones.
How tall are you? Some of the more vertically challeneged amongst us find the standard footpegs to be a bit of a stretch, but that can be fixed in various ways - installing footboards is the most common method.
Without wanting to sound too biased, I don't think you'd regret choosing a Triumph.
