Greenline: excellent pricing, packaging (boxed) and quality.
AquaEssentials/Tropica: surprisingly cost effective given that I ordered '2' vallis mini twister pots and got in excess of 20 good sized specimens! Well packed (boxed) and excellent delivery times.
I would use Greenline for everyday, common stuff, and then use AquaEssentials/Tropica for those special or hard to find plants. I don't really think Tropica stuff will work out that much more expensive than other online shops if the quantity of plants sold in each pot is the same across their range. Now, what would I do with £250 of Tropica plants etc.....