Bitcoin or gold, i may say that both are same, gold in the fiat word is very good as such as bitcoin in online world. if you are holding gold then when ever you are in problem you can get cash immediately by selling or getting loan against gold. and the price of gold is also increasing and decreasing every day. Bitcoin as same in the online world the price is fluctuating and in future the price will be high only

so i will invest in both as both are good for investment.

you are right that both have unique advantages but i think bitcoin is much more better for investment than gold because bitcoin increasing its price too much faster in huge amount and gold are too slow increasing its price , so bitcoin is beneficial .

iam choose both, gold is longterm investment because value posistion gold is equal dollar
in fast growth money iam choose bitcoin

Can I choose both?  Honestly if I have to choose one, I would choose the one tested of time, that is gold.  We know that gold has been here for a centuries now.  Before it was used as a coin/money to buy or to trade something like foods, fruits, animals, fine linen, silk, decors like that.  And it is still existing up to now and one commodity to invest at the moment.  Bitcoin on the other hand really gives us promising income.  Many investors are looking up and buying some bitcoins for investment. 

bitcoin is a long term investment either and it can make you some really good money in my opinion

Not sure if itwill be gold...imagine if they discover tomorrow a giant mine with gold which will be more then all the oil in the world or slat water and what will happen with the priceof gold then.

the problem is how much we have capital to invest at gold and bitcoin, for me invest at both of them is good choice but we must remember to save some amount at fiat for future danger situation.

for long-term gold may be safer, because it is definitely. while bitcoin has an uncertain future.
so all this is just the confidence and trust someone to bitcoin. so I think bitcoin grow better than you buy many bitcoin for the future.
but the long-term investment in bitcoin could also be more profitable when the price was rising very high. so do both quite well.

Diversify is not really a thing that you should consider when you want to invest on something that you think has a huge potential then just go straight ahead for that. Most people will suggest to diversify your investment however if you think that something truly has a huge potential then it is fine to go straight ahead with it