Choosing big lizard (no money/space restrictions), tegu or sailfin?

[Sylphie]

As an engagement token from my fiancee I want a big lizard instead of typical ring. We have both money and space for anything at all really, so it's not really important how big an enclosure will be etc. Of course common sense dictates that the animal price would need to be around 800$, but as for enclosure and care requirement there are no restrictions at all. Also, I don't really mind if it'll be omnivorous, carnivorous or herbivorous, or arboreal/terrestrial. I wolud prefer if the lizard wouldn't be heavier than 25-35lbs and not too aggressive/defensive.

For a long time I was sure I want a black&white argentine tegu, but recently I'm also considering a sailfin dragon (Hydrosaurus pustulatus or amboinensis). There is plenty of info about tegus, but I can't really find much about sailfins other than basic care. If anyone knows someone I could write to and ask some opinions how they are as pets and how working with them looks I would really appreciate it (or maybe someone here worked with them and could tell me what is their opinion about those dragons). I would gladly hear your opinion about what you would choose from these two.
I like tegus more in terms of personality and "pet-ability", but I also fell in love with sailfins and they seem to be more challenging in terms of "taming" them.

Or maybe you have any other reccomendations what I could look at? I'm not really a fan of monitors as I don't like how they look, but I'm sure there are some species of big lizards that I don't know.

Thanks!