It depends, how apt are you at soldering? Do you just want to buy and forget? Do you just want one light or will you be buying again next month? How familiar are you with lithium safety.
If your unaware of lithium’s, read up, see if its something you want to get into, if you don’t, none of these options are suitable.
If your unsure, the hd2010 is a good start, single cell so simple. But, don’t clean contacts and fit king Kong cells, unless you can swap emitters and drivers.
If you can solder and your new to li ion, get a zy-t08, find the thread and links, buy light, fit resistor (for preference variable and dial in the tail cap current) to about 3.5a, instant good thrower.
If all this is foreign, read up first and see where your happy.
If you don’t want lithium, you need to be looking at the fenix primary powered throwers and the cost that involves.
Or, you need to get familiar and happy, get good cells from a reputable dealer, a good recommended charger, a good multimeter, and learn how it all works.
A thrower puts the highest demands in cells, they generally draw the most current, so you have to look after them, think race horse rather than mule.
If your happy with all that and want to just buy one light the tn31 is a good option, but qc seems to be hit and miss.
Other options are the shadow jm26 - single cell, current regulated, cheap throws well, its very under rated. The shadow sl3 provides more flood (3 emitters) with impressive throw, again single cell, current regulated.
As you can see, I’m trying to steer clear of serial battery lights, as I don’t know your experience, I don’t want to recommend something potentially dangerous.
I also can’t say enough, you need decent cells and charger to suit. Panasonic’s, keeppower’s, Samsung’s, sanyo’s etc.