Firstly, congratulations!
Secondly, I voted for the Alpinist. To me, it comes down to the fact that this is a symbol of your graduation, and if it was me, I'd probably end up keeping that sentimental symbol around for as long as possible. (IME sentimental watches tend to stay in the collection.)
I admire Traska, and especially their dive designs, but feel the summiteer is trying too hard to capture Explorer vibes - from the name to the numerals on the dial, etc. While that's fine, of course, (standing on the shoulders of giants and all that - and you want an Explorer-style watch), I feel it might not age well. Eventually you might have an Explorer and then end up with friction in the collection. Or you might, after time with it, just feel it is "explorer-like" and that's what it becomes: a homage, or a tribute - instead of what it should be: a representation of your major milestone!
The Alpinist, on the other hand, is truly doing its own thing - reaching into its own heritage and bringing that storied legacy forward. Sure, it has got some Explorer mythos overlap, but far less overtly and definitely not visually. It's a confident piece with a strong identity, and is part of a legacy that has inspired a dedicated community of folks who love and appreciate it... Cheesy, but inspirational (IMO) nonetheless!
The Alpinist can live happily alongside an Explorer, or any other watch, without feeling too samey, and might therefore be easier to keep, wear, and appreciate over the long term.
Either way you go, though, congratulations again!