The side buildings are quite interesting. I've calculated their %buff efficiency per square. This is actually with the consideration that you'll need at the least the bare minimum number to produce enough frag. for 1 temporary boost every week. This way of thinking is mainly of a player who's fighting only once a week for 30 minutes maximum.
(8x)
Paradise roses =
100%
30min. Produced weekly buff
12,5%
30min./w /square
8-16%
1-2%
/square
This one produces up to 2 frag./building, hence its efficiency. For rounding purposes I've not taken into account the additional 1/15 frag. after 1w. produced but every 15th week you could get an additional buff, assuming perfect collection streaks.
(15x)
Hidden goods =
100%30min. / 200%
30min.
15-30%
13,33%
30min./w /square
1-2%
I've crossed out the weaker of the 2 versions, since they're not stackable. I have also not taken into account shifts in collecting times. Which would make it a bit more fair but more complex.
(15x)
PY-R8 Maraudar
100%30min. / 200%
30min.
45%
3%
/square
13,33%
30min./w
In conclusion and unsurprisingly paradise roses are the worse in terms of efficiency. Though its redeeming quality is that you need less of them to get the buffs rolling in. Meaning less time is needed to producing them or less luck. They're also providing some %
for those who need it. So, for a more military player they could be surprisingly useful-ish.
The hidden goods however are imo the unsurprising best option for those who want more %
to carry them through though battles and improving their goods supply. To improve their neg. resources. Imho players who are mainly focusing on goods and parttime fight could get most use out of them. Since the %
efficiency is quite large and they're offering some additional %
permanently.
For the more regular fighters, I would go for the PY-R8. It does supply you daily with art. units, which depending on the age you're in, can be useful. Also the %
is extremely good. Though it does suffer from shifting collecting times.
For all the side buildings, they're also all suffering from one critical bottleneck: their buffs ain't stackable and not compatibel. Meaning additional ones compromising their %buff/square efficiency but improving their availability. Leaving the paradise roses the weakest of the 3. Even though it's still among the better %
efficient buildings, it greatly suffers from the lack of any other production than fragments. Where hidden goods redeems itself in being fairly efficient with goods production and the PY-R8 record holder in efficiency for units/square, although it's specialised in art. units.
Paradise roses are sadly one to avoid unless you really need the %
up ASAP. Otherwise I'd rather advise the hidden goods if the goods supply is not large enough yet, probably best for TAS players to keep up with demand and better for age-rushing players. For general fighters who use art. units regular or are in an age where art. is strong, PY-R8 is a great option.
Personally I'm probably stacking a couple of PY-R8's and opt after that for a lot of hidden goods later down the road; whenever I may age up into the space ages, most art. units aren't that great (except SAV & TAS).