Reddit reviews Heaven's Command

That's where it gets a bit confusing. There were really two British Empires, the first was in North America and we largely lost that with American Independence (although we did hold onto the Caribbean because of the Sugar). That grew up around the same time as the Spanish, maybe displaced by around 50 years. We subsequently used the profits from that to found the Second Empire, which was centred on India and later Africa.

Of course there's a fair bit of overlap between them, but historically it's quite beneficial to distinguish them. With some notable exceptions (the Tasmanians being one, although that was more of an 'on the ground' act than imperial policy) the second was relatively benign. If you're a SJW/Leftie type it's easy enough to pick holes in the imperial project, but there is two sides to the balance sheet and more than usual in the positive column.

It's old now, but if you'd like to read a well written narrative account of empire 'Pax Britannica' by Jan Morris is something of a page turner - https://www.amazon.co.uk/Heavens-Command-Pax-Britannica-1/dp/0571290698/

As to the Spanish. The Spanish use of slave labour for mining silver was easily as bad as the British use of slaves for growing sugar.