Valhalla are currently offering a free plugin from their superb reverb/delay range!
I use several of their plugins and they are light enough in terms of resource load for stage use but they still sound great. Their focus is on function - don't expect glitzy graphical interfaces - but to me that makes them easier to use.
From their own information
I used it to add spacious reverb to an ambient track I was finishing off tonight. I was quite impressed with it.ValhallaSupermassive is designed to blow your mind and your music to new levels of consciousness and experience! Luscious clouds of reverb, otherworldly delays, swelling waves of feedback unlike any you’ve heard before.
And it's free. So what's not to like?