Bought 5th slot, which gold purchase nexr?

Wow six?! Ok thanks.

Buying two Orkans and then concentrating on levelling them up will never be a waste. The general advice of weapons before 'bots is good - no point having a fabulous shiny new special 'bot if you can't properly take advantage of it with an effective load-out.

That said, if you have workshop points and plasma weapons a Plasmahad is one of the best general-purpose 'bots in the game - I would recommend getting one as a priority.

4 Orkans is preferred.

Thread moved to Tips and Advice.

The order of gold purchases after the 5th slot which I would suggest is:
2 Orkans, Galahad, 2 Orkans, Fury / Lancelot, 4 Aphids / Ancile (If Lancelot), Fury / Lanclot, 2 Zeus

I'd echo what others have said. Weapons before bots, so that when you get the bot you have something useful to put on it. Can't go wrong with Orkans but I'd say just two to start with - get used to how they work and how that fits with your playing style and that should inform your decision making process for the future bots and weapons choices.

Although it won't feel like it initially, WSP does gather quite fast and you'll eventually find you have a surplus of it, so don't be afraid to experiment with that - at the lower levels plasma is super effective; less so as you rise because of all the shields, but never entirely redundant.

Lotsa thanks guys.

CONGRATS!
It's a difficult test and kind of a patience game to squeeze 5k Au and resist spending it early!

After I did 5th slot, I went for Galahad (+plasma) and just recently followed it with 2 Orkans.
Either way you need both and the final answer may depend on your hangar and typical opponents you are facing.
If (1) you feel like having a bigger problem with shielded bots - go for orkans, in case (2) some a bot with extra survivability is a missing piece of your hangar - take Gala first.

Lances are primary targets and don't survive too long. On top of that comes the shield nerf and abundance of splash munitions. Overall I think in average I tend to win more skirmishes with Lances than loosing to them.
It's big, slow, all-favorite target. Even with some extra HP it's simply too clumsy.
Just my 0,02$

I acquired a Lance ages ago, persevered with it for a while but eventually gave up and shelved it.  I described it on here once as a slow moving rocket magnet.  But having moved up a few levels (I'm now almost 10/10) and found I was struggling to be competitive for damage dealt, I re-jigged my hangar a bit and brought the big boy out of retirement.  The results have been quite satisfactory - you have to move cautiously and select your targets carefully but I'm finding it quite effective now.

If you check out the top league players, you'll find quite a healthy smattering of Lancelots in their hangars which suggests they may be worth sticking with - especially having spent all the gold on them in the first place!