I come from a Muslim country, so I guess I qualify. 
My first encounter with Buddhism was back in college, when a philosophy major friend asked me to ghost-write their work on Dōgen’s “Oneness of Practice-Realisation” compared to Kantian ethics.
Suffice to say, I hadn’t an inkling of what Buddhism was. Armed with Wikipedia and some Shōbōgenzō snippets, somehow I managed to get a passing grade. The meta-irony of the whole episode about the very concept Dōgen was explaining, is abundantly delightful to me. 
But I was struck by the opening paragraph of Bendōwa (The Sermon on the Effort-Way). I can’t remember what translation it was, but this is how I read it:
All buddhas and tathāgatas, in directly transmitting the wondrous Dharma and realizing unsurpassed awakening, possess a supreme and unconditioned art. Entrusted only from buddha to buddha and admitting no deviation, it takes as its standard the samādhi in which realization is personally received and enjoyed. To move freely within this samādhi, upright sitting in Zen is the true gate.
Something about the framing, the directness of the aim, was powerful to me. It’s a visceral, embodied directive, explaining the Buddha art, which is personally verified, enjoyed, and sitting upright is the true gate for it’s cultivation.
To be honest, it took me a long while to figure out what Arhat even meant.
What inspired me to practice Boddhisattva Way was embodying Buddha, in his methods and practice, to be able to sit comfortably at all.
So for a while, I tried sitting still. I liked it, and I began to realise just how we ourselves or the world make it difficult for us to sit comfortably. And on the finer points of just how to sit, I ventured into the sūtras.
My first foray into the scriptures were Lotus Sūtra, which, I don’t know if you’ve ever tried to read as a first sūtra — it’s very hard to make any sense of it! All these weird gods and bodhisattvas and upset monks and drama…
So I made my way into Pāli Canon. That seemed more immediately useful, relevant, sober-headed compared to the grand drama.
Of course, as I suspect anyone who has a hint of interest across traditions could confirm, I began to have this “Wait, are Mahāyāna scriptures then so fake?” internal debates and inquiries. Lateness in transmission, altered doctrines, genuine-fakeness…
But, Nikāyas seemed more grounded and relevant to my practice, so I set aside the whole I-don’t-know-what-Mahāyāna debate, with a side of guilty pleasure of indulging in Dōgen’s expositions here and there.
And what I’m about to say may sound strange, but I realised I was practicing only because Dōgen left instructions. In a sense, I believe in the Buddha because I believed in the Dōgen who believed in the Buddha.
And so it is with all traditions. It’s through the painstaking tradition of monks, nuns, layfolk of all sorts, that we are even in the business of Dharma.
And this realization of faith, made me humble for trying to figure out why Dōgen, the reason of my faith in the Buddha in the first place, wouldn’t stop talking about the virtues of Lotus Sūtra.
So I came back, nominally third time to Lotus Sūtra, and this time around, it didn’t seem like an outrageous space-opera, or a discarding of Nikāyas. In fact, I wonder if anyone without a solid background in Nikāyas could even make sense of it at all.
Suddenly it didn’t seem like a “replacement project” or “a fake article”, but just so, another line in the tradition of Buddhadharma, written for a Buddhist audience already, a call for reunion, and a celebration of the sameness of the Buddhist path, despite myriads appearances.
To be a Mahāyāna student is an arduous task. First you gotta learn the suttas, then the Abhidharmas, then the commentaries, then the violence of Prajñaparamita upon the Abhidharmas, and so on…
But in my ignorance, this is what I cherish: that people wrestled with the same points, and debated fiercely and gently for millennia, all because they were inspired with the same image of Shakyamuni sitting in samādhi.
Looking at this image, this is probably nothing like what Shakyamuni ever looked like. He was depicted bald, to begin with; and unless some magical realities exist that I do not know, he can’t have a head like that.
But still it continues to inspire people, because people see in it a reflection of what Shakyamuni stood for, who could in this instance, happen to look like he has his hair braided just so. Does it make it any less true, that he is depicted as being crowned in his samādhi?
(And after all, I might still be wrong, and he might’ve really had his hair like that. That would be weird for me, but I’d like to think I could handle it. )
In this image, arhat, tathāgatas, buddha might just be words, after all. Somewhere in the suttas, it says that tathāgatas can’t be found to be real or so, and I’m probably missing a point there, so don’t quote me for anything other than my article of faith.
I’ve been moved to be like the Buddha nevertheless, to be able to sit still, to hold everything in stillness, as a direction of my faith: That I see the merit in striving to be just so as Buddha had and Buddha was, to reach and elucidate his unsurpassed samādhi.
So, long story short: Why did I choose Mahāyāna (I couldn’t really say “over Theravāda” though, since I consider myself a student of Theravāda just as much)?
Well, because somewhere in my shameless youth, I had the most fortunate indecency of ghost-writing a philosophy paper on a maddening Zen poet, and I took the joke seriously. 