Obviously... you're the one to make the ultimate decision. Here's what I think I'd do if I was you.
Make a list of everything you'll need for your system - tank, stand, heaters, skimmer, powerheads, sump (if applicable), power strips, lighting, timers, live rock and substrate, test kits, refractometer, thermometers, mixing tubs/heaters/powerheads for salt water storage, etc. Everything. Then methodically research each thing and figure out what brand/size you want to put in your tank. Check internet stores for prices and jot those down and you'll end up with a nice shopping list.
This does two things for you. It forces you to research all the components that go into a system and learn pros/cons and various brands and perhaps their reliability and gives you a basic starting point for what it's going to cost you. I say "starting point" because there is always more "stuff" that you'll need, or have to rebuy because you decided wrong.
The other thing it does for you is buys you time! Sounds like you need to mull this plunge into aquarium keeping over a bit, and this keeps you involved in the project, forces you to learn learn learn, and gives you time to really decide if this is something you want to do. Unlike other hobbies, it's tough to just "get your feet wet" to see if it's something you like. Sure... smaller tanks (10-20g) are less expensive to get going, but require more frequent maintenance than bigger tanks. There's just less volume of water to work with and water parameters (salinty, pH, temp, alk
, etc) can vary much more quickly. Many beginners start with small tanks because they think they will be easier but it is exactly the opposite case. They eventually get frustrated and walk away from it all.
There's a thread here somewhere that talks about how much $$ people have put into their tanks. I tried to find it because I think for costs, it'll give you a good idea what you're getting in to. But I can't find the thread. Maybe someone else will have better luck with the search. It can't be more than 6 months old.
Anyway - I will say that a 46g would be easier to do water changes on, just because there's less water to change. I have a 46g, and do a 4+gallon change per week. That's just one bucket full of water, so it's no big deal. BUT... if I had it to do over again, and I had the room to do it, I would've gotten a bigger tank. Even with a 46g though, it'll be easy to put $3000 into it in the first year.
If you haven't already - get a couple books and read them before you decide if this is something you want to do. One is Michael Paletta's "The New Marine Aquarium" and the other if Robert Fenner's "The Conscientious Marine Aquarist". Both are great overviews (Paletta's being an easier read, and probably should be read first) of the hobby and might give you more insight to help make the decision.
And of course keep asking questions here! Welcome aboard!