1. Know your purpose. What are you buying this amp for? Practice at an apartment? or play with your band with a drummer. With that said, you need different types of amp for the right purpose. If you're practising with your band and doing shows, then yea, tube is the best, something more than 20W (assuming you'll play for Nepali functions and NOT Madison square). Then buy a bunch of analogue pedals for effects according to your taste. Tweak and get your won tone
But if you're using it to practise in an apartment with a low volume, then tube amp is basically worthless. Tube sound good only after you break into the tube with loud volume. For practise, even that MG50dfx is too loud. Go for smaller Watt or get modelling amp (Line 6, Peavy Vyper, Roland ets ets). They're small, not the greatest digital crap, but you can practise at low volume and headphone. Remember a 15W tube amp is as loud as 50W solis state amp. Careful with that.
2. You choose what is right for you. Don't be greedy and buy things that you don't need or will use soon. You'll regret it.