What do you define as top of the line? Brand, price, style, features? What is top of the line for some may be closer to the bottom for others if it does not meet their style of diving, fit their needs, or is outside their budget.
Are you going to be a strictly warm water diver who only dives when they travel?
Will you do any local diving in less than optimal conditions?
What are you interested in as far as types of diving?
Any interest in technical diving down the road?
Do you want to buy once or buy multiple times as your interests change?
There is one TYPE of BC that will adapt and meet all these needs. It'll handle warm water, cold water, be very travel friendly, modular so that you can replace components as they wear or your needs change, be able to give you a total custom fit, and be had at very reasonable cost. Heck you could put on together used for under 300 bucks if you know what you are looking for. And not much more than 400 for a new one.
That would be a back plate and wing from any number of manufacturers. I have an article on them for recreational, new divers, and students. All I need is an email to send it to.
Or you could look at names instead of features and buy based on that. Which may mean you spend twice what you need to.