If you want to go domination, a good tech to take is Chemistry or better still steel. Then you upgrade your maces to grens . You can even turn off tech at steel and use all the gold for upgrades and culture while you burn burn burn.
If you set up a food heavy empire you're better going Nationalism for Nationhood to draft.
It all depends on how well you've set your empire for the victory condition and the map set up in each case. The free tech from Liberalism is a key part to it, but still is only a part.
I personally think Liberalism is over-rated and a lot of it's attraction is the techs you pick up on the route, which are all good and trade bait.
On a water map, the best tech to take can be Astronomy because it opens trade routes and you can build Galleons ahead of everyone to jump a neighbor over the sea.
One more point, a Great Merchant can net you around 2000 gold which can easily turn into 2200 beakers, about the same as the free tech would give you. The gold at the right time and a bunch of knights which you got by going Guilds instead of Paper can clinch the victory by taking the best land or breaking the biggest threat.