Big Sam has handed starts to Niasse, Dominic Calvert-Lewin and new signing Cenk Tosun since he was named manager and admits nobody has nailed down a regular place in the XI.
Asked who he would say is his No.1 striker, Allardyce said: “I wouldn't.
“We don't know too much about Cenk yet, he's coming from abroad which is the hardest thing to do as a frontman – succeed in the Premier League and especially so in January.
“We have got to provide a better service for him to score those goals. But if you look at Oumar and Oumar's minutes-per-goals, it's exceptionally good. Sadly on Wednesday night he missed two very, very good chances. It could've been 2-0 and then after the kick-off it should've been 3-0 but he just over-hit that one.
“He could've had at least two goals in that game for us which would've been fantastic for us and him but the most important thing at the end of the day was we won, which we did.
“But he appears, at the moment, to be the best player to score goals for us at the moment."
Meanwhile, Allardyce is pleased with the form of Cuco Martina.
“One of the most important things is how well you defend when you have not got the ball and you have to do that an awful lot in every game," Allardyce told evertontv.
“Cuco's stats, both defensively, and certainly in possession, are good – so, while he does not go dashing forward, he passes just as many balls forward as anybody else.
“I think he was only two forward passes behind Seamus Coleman on Wednesday, but Seamus has got this high-energy stuff, this ability to get forward, which is impressive.
“Cuco is more moderate in those terms. But Cuco is very comfortable, he never looks flustered, he looks calm. Certainly, from our point of view – and he is not playing in his natural position – he is doing a very, very good job.
“I do not quite know where we might have been without him."