Fair disclosure - I own the tequila brand Voodoo Tiki Tequila.
Generally speaking, 100% blue agave tequila is better than mixto tequila. A 100% blue agave tequila must by law be marked as such. If your bottle does not say 100% blue Agave on the bottle front it is a mixto, and thus inferior.
Once we're talking 100% blue agave the rest is going to depend upon your personal taste. Silver tequila (Sometimes called blanco or platinum) is not aged. Aging times can result in higher prices (and taste fluctuations) but despite the price increases the processes do not make for "Better" tequila. Different, and higher priced, but not necessarily better. It's a personal taste issue.
All quality brands of tequila have a "Profile", and what is best to you may not be best to someone else.
If you were asking because you wanted to buy a gift for someone, and we're looking for "Top End", many brands make limited edition, ultra premium editions of their products. Jose Cuervo's is known as "Family Reserve." Patron's Ultra Premium is called "Burdeos." Don Julio makes an ultra premium called "1942." We also produce a three year Extra Anejo called Voodoo Tiki Private Family Collection. It's limited to 1,000 bottles yearly and ships in a hand carved tiki.